Interspecific competition for a food resource (fish eggs) was examined in a laboratory setting between two common benthic organisms of the Great Lakes, the slimy sculpin (Cottus cognatus) and crayfish (Orconectes virilis). In monospecific tests, the median egg predation in aquarium microcosms ranged from 2.5 eggs/d for the sculpin to 3.0 eggs/d for the crayfish. In mixed-specific tests, sculpin feeding rates were no different than in monospecific tests. Feeding rates for crayfish, however, were significantly reduced by the presence of sculpin. In mixed-speciec treatments in which small refuges were included in the aquaria, crayfish predation of eggs was 50% less than in the monospecific tests, i.e., 1.5 eggs/d, and , crayfish went on 93% fewer excursions outside refuges, spent 94% less time outside refuges, and engaged in 83% fewer feeding bouts than sculpin. When no refuges were provided, crayfish ceased feeding (0 eggs/d). These results suggest the potential for a asymmetrical copetitive interaction in a natural setting in which crayfish may be forced into a subopimal diet by such an interaction with the slimy sculpin.
Additional publication details
Competition for food between crayfish (Orconectes virilis) and the slimy sculpin (Cottus cognatus)